Multistage compressor



P 'I $19745 H. R. RICARDO v 2,373,779

IIULTIS'IAGE cournnsson.

Fil'ed Sept. 16, 1942 s Sheets-Sheet 1 v April 1945. H. R. RICARDO2,373,779

- MULTISTAGE COMPRESSOR Filed Sept. 16, 1942 s Sheets-Sheet 2 F/G.3.j

{1 i f Q t i H- F a 1 D/ i Q Fl H/ Q r 0/ Q H2 I g Invent By If Mttorney Patented Apr. 17, 1945 UNITED STATES PATENT O R MULTISTAGECOMPRESSOR Harry Ralph Ricardo, London, England ApplicationSeptember-16, 1942, Serial No. 458,547

In Great Britain September 29, 1941 6 Claims. (Cl. 230-184) Thisinvention relates to multi-stage compresject to provide a compact andsimple construction adapted more especially for the compression of airor gas. According to this invention in the compressor a higherrotational speed is employed than in the subsequent stages, the firststage being operated by a crankshaft which is rotated at a speed greaterthan that of the crankshaft by which are operated the pistons of thesubsequent stages. There is at least one cylinder with piston thereinconstituting the first stage this piston being reciprocated by acrankshaft driven at relatively high speed and pistons in cylindersconstituting the subsequent stages which are reciprocated by a secondcrankshaftthe first stage of 'sors of the reciprocating type and has forits obdriven at a lower speed and conveniently through gearing from thefirst crankshaft. The valves of each cylinder in the first stage arepositively actuated mechanically, while the valves of the cylinders ineach subsequent stage operate automatically. These inlet and deliveryvalves. of the first stage are of the piston type and areoperated by ashaft rotating at half the speed of the crankshaft of the first stage,and the opening and closing of the inlet and delivery ports is effectedwhile these piston valves are moving at their maximum velocity, that isduring the middle portion of the stroke of each valve. Thetshaft whichoperates these piston valves is conveniently the crankshaft whichreciprocates the pistons in the cylinders of the subsequent stages thesecylinders and pistons being disposed coaxially with the piston valves towhich those higher stage pistons are connected so that they are actuatedthrough the valves. Each of the latter thus acts as a cross-head towhichis connected on the one hand the piston of a higher stage and on theother hand a connecting rod running from a crank on the secondcrankshaft. In a convenient arrangement the delivery valve of the firststage is connected to and serves as a cross-head for the piston of thethird stage, this valve being actuated from a crank on a crankshaftdriven 1 through gearing at half speed from the crankshaft whichoperates the first stage. To a second crank on this half speedcrankshaft isconnected 'the inletor suction valve of the first stagecylinder and this valve in turn acts as a cross-head for and isconnected to the piston of the second stage cylinder. .From this pistonmayextend a plunger which reciprocates in the cylinder of a fourthstage. This latter may be omitted if the may be referred to as the maincrankshaft while compressor is constructed with only three stages.

Suitable intercoolers may be provided between the various stages, and anaftercooler may be provided to cool the gas delivered by the last orhighest stage. i

The accompanying draw gs illustrate diagrammatically and by way ofexample a construction of four-stage compressor according to this inven-Figure 2 is a planof the compressor shown in Figure 1. v

Figure 3 is a transversevertical section on the line 3-3 in Figure l,and the broken line-33 in Figure 2, the section showing the piston andcylinder of the first stage, the inlet valve therefor, and thecylinders, pistons and valves ofthe second and fourth stages.

"Figure 4 is 'a vertical section similar to Figure 3, but taken onthe-line l,--& in Figure 1 and .on the broken line 4-4 in, Figure 2',and'show ing the piston and cylinder of the first stage,

the delivery valve for that cylinder, and the cylin- -der and piston ofthe third stage.

. There are two crankshafts of which" the one 'A the other B may .be'referred to as the second crankshaft or layshaft. The compressoris'driven by power applied in some convenient manner and fromasuitablesource to the main shaft A, and the layshaft B is driven bygearing C from the shaft A so that the. layshaftB will be rotated athalf the speed of the main shaft These'two' shafts A and B are paralleland atno, great dis-,

tance apart with the axis of the shaft B lying a horizontal plane abovethe similar plane in w ch lies the axis of the shaft A, as can be seen mFigures and 4. The vertical plane in which lies the axis of the shaft Band'the axes of the pistons driven from that shaft is set back behindthe vertical plane in which lies the axis of the cylinder of thefirststage as can be seen in Fig- -ure 2 as-well as in Figures 3 and 4.Considered in plan, as seen in Figure 2, the cylinder D of the firststage with the piston E therein appears as having at one side of it thecylinders F and G with the piston valves H and J therein. Coaxial withthe cylinder F'and above itare the cylinder elevation of the I K of thesecond stage with the piston L reciprocating therein, and the cylinder Mof the fourth stage with the plunger piston Ntherein. Coaxial with thecylinder G and above it is the cylinder of the third stage with thepiston P which is reciprocated in it.

Th piston valves of the first stage are hollow and the suction valve H.controls an inlet port D to the first stage cylinder D and an inlet portF from the atmosphere to the valve cylinder F as seen in Figure 3. Thevalve J controls the delivery port D from the cylinderD and thecompressed air passes through the valve J and cylinder G into thepassage G which communicates conveniently with an intercooler ofsuitable type which is not shown in the drawing. From this first stageintercooler the air passes the suction valve K into the secondstagecylinder K whence it is delivered past the delivery valve K to a secondintercooler, also not shown in the drawing. From this second stageintercooler the air goes past the suction valve 0 into the third stagecylinder 0 and thence past the delivery valve 0 to a third stageintercooler which is not shown. Finally the air enters the fourth stagecylinder M past the valve M and is delivered past the valve M i Thehollow piston valves H and J are substantially similar in their generalstructure with ports formed in the walls of their upper parts. In thevalve H which functions also as a cross-head, is a partition H belowwhich is carried the gudgeon pin H through which the valve is connectedto the crankshaft B. From this partition'H a coupling rod Q extendstothe piston L of the second stage. This coupling rod has'curved facesat its ends which engage correspondingly curved bearing blocks carriedrespectively by the partition H andthe piston L. By suitable means theends of the coupling rod are maintained in'engagement with the curvedseats in these blocks. The arrangement obviates difficulty which mightarise owing to some lack of alignment between the clinders F and K.There is a similar coupling rod between a partition J in the pistonvalve J, which also functions as a cross-head for the gudgeon pin J andthe piston P of the third stage.

By leading the air from the first stage cylinder D into the end of thecylinder G beneath the piston P in the'c-ylinder O of a higher stage thepressure difference is reduced on the rings of the piston of the higherstage.

There may be a throttle valve of suitable form .in the induction passageleading to the suction valve inlet port F In'the head of the cylinder Dstage cylinders are of some type which will operate automatically. Inthe case of the second stage cylinder K each of the valves K and K" is adisc -which is mounted freely, except for a light spring, between aperforated seat member and a retaining member. The ports controlled bythese valves are in the head of the cylinder K. with regard to the thirdstage the piston P is of trunk form with the trunk of substantiallength. The' end of the cylinder 0 and the face of the piston areconical the ports being in the sloping end of the cylinder. The inletvalve 0 is preferably of the poppet type and the delivery valve 0 is adisc acted on by-a spring.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a multi-stage compressor of the reciprocating type the combinationof at least one cylinder with piston therein constituting the firststage of the compressor, at least one other cylinder with piston thereinconstituting a subsequent stage, a crankshaft to which is connected thepiston in the said cylinder of the first stage, a second crankshaft towhich is connected the piston in the said cylinder of a subsequentstage,

. shaft is driven.

2. In a multi-stage compressor of the reciprocating type the combinationof at least one cylinder with piston therein constituting the firststage of the compressor, at least one other cylinder with piston thereinconstituting a subsequent stage, a crankshaft to which is connected thepiston in the said cylinder of the first stage, a second crankshaft towhich is connected the piston in the said cylinder of a subsequentstage, valves associated with the said cylinder of the first stage,means by which these valves are actuated from the said secondcrankshaft, valves associated with the said cylinder of a subsequentstage with means by which these valves are actuated automatically, andmeans whereby the said second crankshaft is rotated at a speed which isless than the speed at which the said first crankshaft is driven.

3. A multi-stage compressor of the reciprocating type comprising thefeatures as set out in claim 2 in which piston valves connected to andreciprocated by the said second crankshaft function as the inlet anddelivery valve of the said cylinder of the first stage.

4. In a multi-stage compressor of the reciprocating type the combinationof at least one cylinder with piston therein, constituting the firststage of the compressor, at least' two cylinders each with a pistontherein and constituting subsequent stages of the compressor, acrankshaft to which is connected the piston in the said cylinder of thefirst stage, a second crankshaft to whichare connected the pistons inthe cylinders of the subsequent stages, piston valves connected to andreciprocated by the second crankshaft these valves functioning as theinlet and delivery valves of the said cylinder of the first stage andbeing respectively coaxial withthe cylinders of the higher stages,valves associated with the said cylinders of stages subsequent to thefirst stage with means by which these valves are actuated automatically,and means whereby the said second crankshaft is rotated at a speed whichis less than the speed at which the said first crankshaft is driven.

5. In a multi-stage compressor of the reciprocating type the combinationof at least one cylinder with piston therein constituting the first stae of the compressor, at least two cylinders each with a piston thereinand constituting subsequent stages ofthe compressor; a crankshaft towhich is connected the piston in the said. cylinder of the first stage,a second crankshaft to which are connected the pistons in the cylinderof the subsequent stages, piston valves connected to and reciprocated bythe second crankshaft these of the said cylinder of the first stage andbeing respectively coaxial with and acting as crossheads for the pistonsin the cylinders of the higher stages, valves associatedwith the saidcylinders.

. valves functioning as the inlet and delivery valves of stagessubsequent to the-first stage with means I by which these valves areactuated automatically, and means whereby the said second crankshaft isrotated at a speed which is less than the speed at which the said firstcrankshaft is driven.

' 6. Ina multi-stage compressor of the reciprocating type; thecombination with at leastone cylinder with piston therein constitutingthe first stage of the compressor, at least two cylinders f each withpiston therein and-constituting subsequent stages of the compressor, atleast, two of these cylinder of subsequent stages being coaxial with thepistons therein connected,'a crankshaft.

to which is connected the piston in the said cyl- 1 inder of the firststage, a second crankshaft to 1 matically, and means whereby the saidsecond crankshaft is rotated'at a speed which is less than the speed atwhich the said first crankshaft is driven, 20

HARRY RALPH RICARDO.

